JP2503344B2 - Microwave detector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave detector for detecting and notifying a microwave emitted from a measuring instrument or the like, and particularly to a microwave from a device to be detected and a microwave other than the objective. Regarding the technology to distinguish.

[0002]

2. Description of the Related Art There has been known a microwave detector configured to detect a microwave emitted from a radar type speed measuring device and generate an alarm. In the case of general traffic monitoring radar type speed measuring equipment, 10G
Hz band (X band), 24 GHz band (K band), 35
Microwaves in any band of the GHz band (Ka band) are used. A microwave detector having a speed measuring instrument of this type as a detection target device receives the microwave of each band by a circuit of a super-heterodyne system. At that time, the local oscillation frequency is swept to widen the reception band band, and further the band sweep is stopped for a certain period of time each time a signal is received to ensure detection, and the heterodyne at the signal detection time when the sweep stops. The signal waveform of the reception characteristic is divided into a time above a certain value and a time below a certain value apart from that, and discrimination is made based on the ratio of each time in each band reception time, the position where it occurs, and the difference in the number of occurrences. A method is already known, and for the 10 GHz band and 24 GHz band local oscillation frequencies in the above detection, two frequencies from a plurality of higher harmonics including a fundamental wave simultaneously emitted from one local oscillator are used. Is selected and used for frequency mixing at the same time,
The band is swept according to whichever of the 10 GHz band and the 24 GHz band is the target frequency band, 3
For the local oscillation frequency of the 5 GHz band, the frequency from another local oscillator is the 10 GHz band and the 24 GHz band.
It is used by switching to the Hz band local oscillator. Ie 10G
Microwave detectors are known which temporally switch between two local oscillators, one for the non-time-switching receiving means in the Hz band and the 24 GHz band and the other for the 35 GHz band local oscillator.

[0003]

Even if the microwave of the target band is detected by the microwave detector as described above, it cannot be determined that it is the microwave from the device to be detected, and other microwaves are not detected. It may be undesired microwave from some signal source. This limits the reliability of the actual use of this type of microwave detector.

A general microwave detector has a mixer portion exposed inside the throat opening of a horn antenna, and has a microwave local oscillator for frequency mixing in a shield box inside the throat antenna. Since the microwave frequency of the oscillator is emitted into the space at least once and then enters the mixer section, conversely, not only the fundamental wave frequency from the local oscillator but also its higher harmonic frequencies are transmitted from the throat opening of the horn antenna. It is unavoidable that the included microwave leaks to the outside. Therefore, when a plurality of microwave detectors are used relatively close to each other, the leaked microwave from the local oscillator of one microwave detector is received by another microwave detector, and the leaked microwave is targeted. An alarm may occur in the other microwave detector despite the fact that it is an outside microwave. The above situation occurs due to the combination of the frequency of the leaked microwave from the local oscillator and the reception band.

Particularly when the leaky microwave frequency is completely included in the frequency band of the target band, it can be said that the conventional method of discriminating the signal processing by the time and the heterodyne reception characteristic cannot discriminate, and therefore, the target band frequency. Since it is not possible to judge which one is detected, even if only one of the leaked microwave and the leaked microwave is detected, false alarms increase even if the leaked microwave is detected as a notification that the target band is detected. On the contrary, if the notification is not made, the function as the microwave detector cannot be fulfilled. Furthermore, when both the target band frequency and the leaked microwave exist at the same time, there is no means for detecting the target microwave while avoiding malfunction due to the leaked microwave.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to make it possible to distinguish between a microwave from a device to be detected and a microwave other than the target as much as possible. It is to provide a wave detector.

[0007]

SUMMARY OF THE INVENTION In the first invention, an attempt is made to distinguish between a target radio wave and a non-target radio wave by paying attention to the difference in their spectral characteristics. That is, the microwave detector according to the first invention comprises a super-heterodyne receiving means for repeating the receiving operation of a plurality of target bands and one reference band set in the microwave band in a time division manner, and each of the bands by the receiving means. The signal discriminating means for discriminating the reception output of each of them to generate a detection signal, and the notifying means for performing a predetermined notifying operation in response to the output of the signal discriminating means, the notifying means of the plurality of target bands. A signal processing means for performing a notification operation when a detection signal is output from the signal discriminating means for any one of the target bands other than one specific band, and a detection signal for the specific band from the signal discriminating means And a signal processing means for performing a notification operation when the signal for discriminating the reference band is not output from the signal discriminating means at the same time. It was that there was example.

In the second invention, the target radio wave and the non-target radio wave are distinguished not only by the difference in the spectral characteristics but also by the difference in the level characteristics. That is, the microwave detector according to the second invention comprises a super-heterodyne receiving means for repeating the receiving operation of a plurality of target bands set in the microwave band and one reference band in a time division manner, and each band by the receiving means. A signal discriminating means for discriminating received signals from each other to generate a detection signal, and a detection signal output from the signal discriminating means at the same time for one specific band of the plurality of target bands and the reference band, Detection sensitivity switching means for returning the detection sensitivity of the specific band in the signal discriminating means to the original high sensitivity state after lowering it for a fixed time, and a predetermined state in response to the control state by the switching means and the output of the signal discriminating means. And a notification means for performing a notification operation, wherein the notification means includes the signal discriminating means for the target band other than the specific band. And a signal processing unit that performs a notification operation when a detection signal is output from the detection unit, and the detection signal of the specific band is output from the signal discrimination circuit in a state where the detection sensitivity of the specific band is set high, and Signal processing means for performing a notification operation when the detection signal of the reference band is not output from the signal discrimination circuit at a time, and the specific band from the signal discrimination circuit in a state where the detection sensitivity of the specific band is set low. And a signal processing means for performing a notification operation when the detection signal is output.

In a third aspect based on the first or second aspect, the super-heterodyne receiving means includes a double super-heterodyne circuit for receiving the target band, and a local oscillator part of the double super-heterodyne circuit. And a control circuit that suspends the function of the frequency mixer and switches to a single superheterodyne circuit to receive the reference band.

[0010]

[Function] The microwave from the detection target device such as the radar type speed measuring device is one of the plurality of target bands.
It has a narrow spectrum width, and almost no incidental spectrum such as harmonics. On the other hand, non-target radio waves, such as microwaves leaked from the local oscillator of the superheterodyne receiver circuit, which are intended to be distinguished from the target radio waves have a characteristic of a large number of incidental spectra accompanied by harmonics of a considerably large level, and the specific band It includes not only the spectral components belonging thereto but also the spectral components belonging to the reference band. Therefore, in the microwave detector of the first invention, when the detection signals are generated at the same time in both the specific band and the reference band, the received radio wave at that time is regarded as the non-target radio wave. When the detection signal of the specific band is generated and the detection signal of the reference band is not generated at the same time, the received radio wave at that time is regarded as the target radio wave, and a predetermined notification operation is performed.

In the second invention, not only the difference in the spectral characteristics between the target radio wave and the non-target radio wave as described above but also the characteristic that the target radio wave has a higher level than the non-target radio wave is utilized. Distinguish out-of-purpose radio waves. That is, if the detection signal is obtained at the same time in the specific band and the reference band, it is highly likely that it is a non-target radio wave,
In that case, the detection sensitivity of the specific band is lowered for a certain period of time. When a detection signal is generated in the specific band while the detection sensitivity of the specific band is low, the received radio wave is regarded as the target radio wave, and a predetermined notification operation is performed.

In a third aspect of the invention, the means for realizing the first or second aspect of the invention temporarily stops one local oscillator of the conventional constituent circuit, or uses a relatively simple bypass circuit means and switch means as one. Since it is shown that it is only added to the mixer section, the cost increase due to the increase of parts and the increase of the external dimensions, etc. at the time of implementation are minimized, and the development and manufacturing are simplified.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic structure and operation of a microwave detector common to the embodiments of the first and second inventions will be described with reference to FIGS.

In the microwave detector of the embodiment described below, the X band (10.475) is used as the three target bands.
~ 10.575 GHz and K band (24.050)
24.250 GHz) and Ka band (34.200-
35.300 GHz) and one reference band (11.428 to 11.688 GHz) are set, and the four bands are repeatedly received by the super-heterodyne receiving circuit in a time division manner.

In FIG. 1, microwaves from the outside are caught by the horn antenna 1, and the first mixer 2 produces the first microwave.
The frequency is mixed with the microwave from the local oscillator 3. As the first local oscillator 3, there are two oscillators 3a for the X band, the K band, the reference band, and the Ka band oscillator 3b.
And both oscillators 3a and 3b are sweep drivers 4
It is driven by a and 4b and alternately oscillates. As shown in FIG. 2, the sweep driver 4a changes the output frequency of the oscillator 3a from 11.455 GHz to 11.715 GHz.
Then, the output frequency of the oscillator 3b is changed from 33.060 GHz to 3 by the sweep driver 4b.
It is swept up to 4.050 GHz. This operation is repeated at regular intervals. The fundamental wave of the oscillator 3a is used for reception of the X band and the reference band, the second harmonic of the oscillator 3a is used for reception of the K band, and the output of the oscillator 3b is K.
Used for receiving a band.

The first intermediate frequency signal from the first mixer 2 is input to the second mixer 7 via the amplifier 5 and frequency mixed with the output of the second local oscillator 6. The output frequency of the second local oscillator 6 is switched by the driver 8 in synchronization with the first local oscillator 3. That is, as shown in FIG. 2, the output frequency of the second local oscillator 6 is 1.130 GHz when the first local oscillator 3a is operating, and 1.160 GHz when the first local oscillator 3b is operating. become. First of the above
Switching of the sweep operation of the local oscillator 3 and switching of the frequency of the second local oscillator 6 are performed by the timing control of the microprocessor 12.

The second intermediate frequency signal from the second mixer 7 is input to the detector 10 through the bandpass filter 9 via the analog switch 15a, and the detection output of the detector 10 is input to the signal discrimination circuit 11. .

The output of the first intermediate frequency amplifier 5 is bypassed and input to the bandpass filter 9 through the analog switch 15b. Figure 2
As shown in, two analog switches 15a and 15b
Are complementarily driven on / off by the microprocessor 12. When the analog switch 15a is on and 15b is off, the second intermediate frequency signal is the bandpass filter 9
In this operation state, the reception operation of X band, K band and Ka band is performed.

The first local oscillator 3a operates, and the analog switch 15a is turned off and the analog switch 15b is turned on for a short fixed time immediately after the output frequency of the second local oscillator becomes 1.130 GHz. At this time, the second mixer 7
The second intermediate frequency signal from the amplifier is ignored, and the first intermediate frequency signal from the amplifier 5 is input to the bandpass filter 9.
This operating state is the receiving state of the reference band.

As described above, the three target bands (X
Band, K band, and Ka band) are received by the double superheterodyne system, one reference band is received by the single superheterodyne system, and these receiving operations are repeated at a constant cycle.

The signal discriminating circuit 11 receives the received / detected signals of each band supplied from the detector 10, discriminates whether or not there is a received signal within the time allotted for each band, and The detection signal for each band is supplied to the microprocessor 12.

The microprocessor 12 checks the detection signal of each band from the signal discriminating circuit 11 every time the receiving operation of four bands is completed, and operates the alarm circuit 13 as follows. The alarm circuit 13 includes an LED lamp and a buzzer.

In the microwave detector having the above frequency structure, the third harmonic component of the output of the first local oscillator 3a is included in the Ka band which is one of the target bands.
Therefore, when a plurality of the microwave detectors are present close to each other and the leaked microwave from one is input to the other, a Ka band detection signal is generated by a leaked radio wave not intended. At this time, the fundamental frequency of the leaked microwave (the fundamental frequency of the first local oscillator 3a) is around 11.5 GHz, and the reference band is set to 11.428 to 1 in accordance with this.
It is set to 1.688 GHz. Then, even if the Ka band detection signal is generated, if the reference band detection signal is also generated at the same time, there is a high possibility that the received radio wave at that time is not the target radio wave.

FIG. 3 shows an alarm control operation by the microprocessor 12 as an embodiment of the first invention.

As shown in the flow chart of FIG. 3, every time the receiving operation of each band is completed, it is judged whether or not the detection signals of the X band and the K band are generated (steps 301 and 302). When either the X band or the K band detection signal is generated, step 305 is executed and the alarm circuit 13 is operated.

When neither the X band detection signal nor the K band detection signal is generated, it is next determined whether or not a Ka band detection signal is generated (step 303). If there is no Ka band detection signal, the process ends this time, but if there is a K band detection signal, it is determined whether or not there is a reference band detection signal (step 304). If there is a Ka band detection signal and no reference band detection signal, the process proceeds to step 305 to operate the alarm circuit 13.

In the above embodiment, when the Ka band detection signal and the reference band detection signal are generated at the same time, the alarm circuit 13 may be operated in a mode different from the normal alarm mode. . That is, the LED lamp of a color different from the normal alarm mode may be turned on, or the buzzer sounding or tone color may be changed to the normal alarm mode.

FIG. 4 shows an alarm control operation by the microprocessor 12 as an embodiment of the second invention. In this embodiment, K in the signal discrimination circuit 11
The a-band detection sensitivity is set to high or low by the microprocessor 12.
The detection sensitivity of the Ka band is normally set to a high sensitivity, and the detection sensitivity can be switched to a low sensitivity for a certain period of time under a certain condition as follows. .

The processing shown in the flowchart of FIG. 4 is executed every time the receiving operation of each band is completed. If an X band or K band detection signal is generated, step 401
Alternatively, the process proceeds from 402 to step 407, and the alarm circuit 13 is operated.

If there is no detection signal for both the X band and the K band, the presence or absence of the detection signal for the Ka band is determined in step 4
The determination is made in 03, and if there is no detection signal, the processing of this time is ended. When there is a Ka band detection signal, it is determined whether the Ka band detection sensitivity in the signal discrimination circuit 11 is set to high sensitivity or low sensitivity (step 404). If the Ka band detection sensitivity is high, the process proceeds to step 405, and it is determined whether or not there is a reference band detection signal. If there is no reference band detection signal, the process proceeds to step 407 to activate the alarm circuit 13. However, when there is no reference band detection signal, the process proceeds to step 406, where the Ka band detection sensitivity in the signal discrimination circuit 11 is set to low sensitivity for a certain period of time (after a certain period of time, the sensitivity automatically returns to high sensitivity). ). If a Ka band detection signal is generated with the Ka band detection sensitivity set to low sensitivity, steps 403, 404,
The process proceeds to 407, and the alarm circuit 13 is operated regardless of the presence or absence of the reference band detection signal.

The reference band may be received in the double super-heterodyne system by switching the output frequency of the second local oscillator.

[0032]

As described in detail above, in the microwave detector according to the first aspect of the present invention, the non-target radio wave from other than the detection target device has a spectral component included in both the specific band and the reference band. It is possible to distinguish between the target radio wave and the non-target radio wave by paying attention to the characteristic difference that the target radio wave does not include the spectral component belonging to the reference band.
Further, in the microwave detector of the second invention, in addition to the difference in the spectral characteristics described above, the difference that the target radio wave has a higher level than the non-target radio wave is discriminated to distinguish the target radio wave from the non-target radio wave. be able to. Further, it is not necessary to provide the reference band detection means separately from the target band detection means, and the configuration can be achieved by adding a few additional circuits to the target band detection means as in the third invention. In addition, it is possible to provide a microwave detector that can be manufactured at low cost and can be manufactured easily.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a microwave detector common to an embodiment of the first invention and an embodiment of the second invention.

2 is a timing chart showing an operation of a super-heterodyne receiver in the microwave detector of FIG.

FIG. 3 is a flowchart of an alarm control operation that is a main part of the first embodiment of the present invention.

FIG. 4 is a flow chart of an alarm control operation which is a main part of the embodiment of the second invention.

[Explanation of symbols]

 1 Horn Antenna 2 1st Mixer 3 1st Local Oscillator 6 2nd Local Oscillator 7 2nd Mixer 9 Bandpass Filter 12 Microprocessor 13 Alarm Circuit 15a, 15b Analog Switch

Claims (4)

(57) [Claims] 1. A super-heterodyne receiving means for repeating the receiving operation of a plurality of target bands and one reference band set in the microwave band in a time division manner, and the reception output of each band by this receiving means is discriminated and detected. The signal discriminating means for generating a signal and the notifying means for performing a predetermined notifying operation in response to the output of the signal discriminating means, the notifying means excluding one specific band of the plurality of target bands. Signal processing means for performing a notification operation when a detection signal is output from the signal discriminating means for any one of the other target bands, and a detection signal for the specific band is output from the signal discriminating means, and at the same time. A microphone including a signal processing unit that performs a notification operation when the detection signal of the reference band is not output from the signal discriminating unit. Wave detector. 2. A super-heterodyne receiving means for repeating the receiving operation of a plurality of target bands and one reference band set in the microwave band in a time division manner, and the reception output of each band by the receiving means is discriminated and detected. A signal discriminating means for generating a signal, and a specific band in the signal discriminating means when a detection signal is output at the same time from the signal discriminating means with respect to one specific band of the plurality of target bands and the reference band. From the detection sensitivity switching means for returning the detection sensitivity to the original high sensitivity state after lowering it for a fixed time, and the notification means for performing a predetermined notification operation in response to the control state by this switching means and the output of the signal discrimination means. The notification means outputs a detection signal from the signal discriminating means for the target band other than the specific band. A signal processing unit that performs an informing operation, and the detection signal of the specific band is output from the signal discrimination circuit in a state where the detection sensitivity of the specific band is set to be high, and the signal discrimination circuit outputs the detection signal of the specific band at the same time. When the detection signal of the specific band is output from the signal discriminating circuit in a state in which the detection sensitivity of the specific band is set to be low, and a signal processing unit that performs a notification operation when the detection signal of the reference band is not output. A microwave detector comprising: a signal processing unit that performs a notification operation. 3. The double superheterodyne circuit according to claim 1, wherein the superheterodyne receiving means suspends the functions of a double superheterodyne circuit for receiving the target band, a part of a local oscillator and a frequency mixer in the double superheterodyne circuit. A microwave detector comprising a control circuit for switching to a single super-heterodyne circuit and receiving the reference band. 4. The double super-heterodyne circuit according to claim 2, wherein the super-heterodyne receiving means suspends the functions of a double super-heterodyne circuit for receiving the target band, a part of the local oscillator and the frequency mixer in the double super-heterodyne circuit. A microwave detector comprising a control circuit for switching to a single super-heterodyne circuit and receiving the reference band.